Coring apparatus



March 23', 1943. .1. E. HoFFoss 2,314,352

CORING APPARATUS 2 Sheeis-Sheet l Eiled NOV. 23, 1940 J". ffroffoss.

INVENTOR.

Patented Mu. 23, 1943 John E. Hofloss. Houston.

Tex, assignor to Reed Roller Bit Company, Houston, Tex, a corporation of Texas Application November 23. 1940, Serial No. 366,820 20 01. 255-72) This invention relates to core drilling apparatus and particularly to a means whereby the core barrel or center bit of a retractible core barrel apparatus may beheld down and driven.

In the past, retractible core, barrels have been held down by mechanical latches, which in someinstances served also to drive the barrels. In other cases, suitable splines or keys were used for driving the barrel or the center bit, which replaces coring head on the barrel when drilling without taking a core. In the case of those core barrels which protrude beyond the lower end of the core bit while drilling soft formations springs or the like have also been provided to permit the barrel to retract into the bit when a hard formation is encountered. I

One of the difliculties resulting from the use of a latch such as referred to is the possibility of the latch becoming fouled or stuck and failing to release properly when an attempt is made to withdraw the core barrel or center bit. Also, the latching mechanism was necessarily placed above the upper end of the core barrel, necessitating the use of a drill collar or other member above the bit and extending 'up a considerable distance and providing a keeper for the latch. The spring referred to is also an unwieldy and expensive construction.

It is an object of this invention to dispense with the necessity for the latch and drill collar referred to.

It is a further object of this invention to dispense with the necessity for the spring referred to.

It is a further object to provide an improved driving and hold down means fora core barrel and center bit which will not foul or stick and which may be located within the bit and about the lower end of the core barrel or center bit.

A further object is to provide a mechanical hold down for a core barrel or center bit which will not involve the use of a movable latching part 1 on either the barrel or center bit or the core bit.

Another object is to provide a non-resilient core barrel hold down which will permit retraction of the core barrel when a hard formation is encountered.

Another object of this invention is to provide means whereby the various parts of a core barrel assembly will be kept in tight threaded engage- 7 men with each other during the movement of slush downwardly past the core barrel, particularly where the core barrel is driven from a, point adjacent its lower end.

Another object is to prevent upflow through the core barrel while it is moving down through, the slush into the well.

Other objects and advantages of this invention will become apparent from the following description taken in connection with the accomtion of the opening as by panying drawings wherein are set forth by way of example certain embodiments of this invention.

' In the drawings:

' Fig. 1 is a longitudinal section through a core bit and core barrel held therein by a device constructed in accordance withthis invention;

Fig. 2 is a top plan view of the core barrel assembly illustrated in Fig. 1 as indicated by the line 2-2 of Fig. 1;

Fig. 3 is a side elevation of a part of the core barrel having one portion of the hold down and driving means thereon;

Fig. 4 is a transverse cross section taken along the line 4-4 of Fig. 3;

Fig. 5 is a top plan view of the hold down ring which is mounted in the bit in Fig. 1;

Fig. 6 is a longitudinal cross section taken along the line 6-6 of Fig. 5;

Fig. 7 is a view similar to Fig. l but showing a center bit in place in the bit head instead of the core barrel with a core cutter head which is used when coring;

Fig. 8 is a view similar modification;

.Fig. 9 is a view similar to Figs. 3 and 8 but showing a still further modification.

Fig. 10 is a fragmentary view of a portion of the hold down means within the core bit shown in Fig. 1;

Fig. 11 is a view a form adapted to cooperate tion shown in Fig. 8.

In Fig. 1 there is shown a drill collar I having a core bit 2 secured to its lower end, which bit is constructed in accordance with this invention. The core bit 2 has cutting blades 3 of any desired type and the usual opening 4 therethrough centrally thereof for receiving a corebarrel. The upper portion ofthe opening 4 is larger than the lower portion and secured within this upper porwelding 5 or the like is a hold down and driving ring 6 constructed in accordance with this invention. The interior of the ring 6 is formed with ribs or splines 1 as more clearly shown in Figs. 5 and 6, and these provide driving surfaces 8 facing forwardly with respect to the direction of rotation of the bit when drilling. As shown in Figs. 5 and 6 these ribs are inclined downwardly and rearwardly with respect to the direction of rotation of the bit when drilling, so that the driving surfaces 8 of these splines face forwardly and downwardly.

. Referring again to Fig. 1, the core barrel 9 is provided at its upper end with a fitting I0 having a ball check valve 1 l therein permitting liquid to flow from the barrel as the core rises therein but preventing liquid from washing downward through the barrel. Fitting I0 is provided on its upper end with a spear head 12 adapted to be to Fig. 3 but showing a similar to Fig. 10 but showing with the modificaengaged by an overshot or the like on the end of a wire line for removing the core barrel.

The ball valve ii is normally seated by gravity against the valve seat ring "-0, but the fitting II is provided above the ball valve II with a second valve seat Il-b so that when the ball valve I l is forced upwardly, as by a strong current flowing upwardly past it, it will seat upon the seat "-1) and will close oil the passage of fluid up through the core barrel and out through the fitting II. The purpose of this arrangement is to prevent fluid from flowing upwardly through the core barrel during the time the core barrel is being passed downthrough the drill stem into operative position. During the taking of a core the flow up'past the valve II will be insuflicient to force this valve against the seat ll-b so that flow from thecore barrel during the taking of a core will be permitted.

Above the outlet openings from the fitting In .and below the spear head l2, this fitting is also provided with notches Ill-a each having'one straight wall and one curved wall as shown so that when fluid is pumped downwardly past the fitting l it will be deflected in a circumferential directionwith respect to the fitting l0 and by reaction will cause the fitting In to rotate in a clockwise direction when viewed from the upper end. The purpose of this is that when a core barrel is driven from a point adjacent its lower end, as it is in this case, the threaded connections above the drive, if right hand, will tend to unscrew. The tendency toward rotation of the fitting l0, though slight, will tend to keep all of the threaded connections between the parts of the core barrel assembly tight during the taking of a core.

At its extreme lower end the core barrel carries a coring head l3 having teeth I 4 thereon adapted to protrude beyond the lower end of the bit 2 to cut the core. Suitable core catchers l5 are carthe splines 'I abut against the squared upper ends of the grooves between the spline II. further be noted that the lower ends It will of the Y splines I I are likewise squared and that due to the respective shapes of the splines l1 and the to rotate slightly in one direction or the other until the splines I! will enter the spaces between the splines 'I.-

drilling, both activesurfacesare inclineddownwardly and rearwardly with respect to such diried within the coring head to retain the core in the core barrel once it has been cut.

Between the coring head and the main body of the core barrel is-a section l6 more clearly illustrated in Fig. 3, which is the same diameter as the rema nder of the core barrel inside but which is formed outside with a series of spiral ribs I'I corresponding in number and pitch to the plines or ribs I. These ribs II are adapted to interfit with the ribs I and coact therewith as shown in Fig. 1 to the end that the coring head I3 and the core barrel may be held down in lowermost position while coring, yet capable of yielding upwardly in the event a ha d formation is encountered or it is desired to withdraw the core barrel from the well. It is noted that these cooperating splines or ribs will not become clogged, but on the contrary it has been found in actual practice that the slush used in drilling will constantly wash these'partsand keep them clean.

The splines H are formed on the member I 6 by cutt ng grooves in the original surface of the member I6 and these grooves terminate at their upper ends in squared shoulders I 8 which are in Fig. 3 substantially perpendicular to the direction of the splines at their upper ends. The spiral ribs 1 are likewise formed with their upper ends member l6 moves downwardly into the ring 6 the splines I will engage the slots between the ribs IT. The member I 6 will be rotated and moved downwardly until the squared-up ends of It is further noted in connection with Figs. 3 and 6 that-the splines I and H are not of uniform width throughout their length. Instead, the splines I are narrower at their top than at their bottom ends and the splines II are wider at their top than at their bottom ends. Because of this construction, the parts will fit loosely together so as to permit a limited amount of vertical movementrof the element l6 when the lower portion of the splines II engage the splines! but as the member l6 moves downwardly into fuller engagement with the. splines I the engagement will become tighter so as to allow less free vertical movement.

It will be understood that while the active surfaces on the ribs 01' splines I face downwardly and forwardly and the active cooperating surfaces on the ribs |'I face upwardly and rearward- 1y withrespect to-thedirection of rotation when rection of rotation. It will thus be seen that when the bit is rotated as in drilling, the cooperating surfaces of the ribs or splines 1 and II will act not only to drive the corebarrel and coring-head to rotate with the bit, but will also act to yieldably drive or hold the core barrel and coring head down. The forceflwith which the core barrel ls-held down will depend upon the degree of inclinationof the splines. On the other hand, when the bit is not being rotated, the arrangement shown will offer practically no resistance to a withdrawal of the core barrel.

In some instances it has been found desirable to make the ribs with a greater inclination adjacent the lower ends than adjacent the upper ends thereof as shown in Fig. 8. In this case the lower portions IQ of the splines may be separated from the upper portions 20 by a sharp change.

of angularity as at 2| or this change may be gradual. With this construction of the splines on the core barrel, the splines in the ring 22 in the bit head will be formed with two corresponding sections 23 and 24 of inclinations similar'to the sections 20 and I9 respectively.

Where the form shown in Figs. 8 and 10 is used, the result will be that the coring head may yield upwardly with relative ease when hard formations are encountered because of the slight angularity of the parts 2|! and 23 which will be in use while the coring head is fully projected. However, after the coring head has moved upwardly a relatively short distance the parts I! and 24. of the splines will come into contact with each other and, due to their greater inclination. further upward movement of the core barrel and head will be resisted with a greater force.

The form shown in Figs. 9 and 11 is similar to that just described except that in this case the lower parts 25 and 26 only of the respective splines are inclined and the upper parts 21 and 28 respectively are substantially parallel to the axis of rotation. In this case the portions 21 and 28 will serve merely to drive the core barrel to rotate with the bit when the coring head is fully projected, and the only forces resisting initial upward movement of the barrel will be its own weight plus such force as the slush being pumped through the drill stem against the upper end of the core barrel will apply. However, upon upward movement of the core barrel the parts 25 and 26 will come into contact with a resulting force resisting further upward movement of the coring head.

In Fig. 7 the coring head of Fig. 1 has been replaced with a center bit 29 which is used when drilling without coring. This center bit may be carried on the regular core barrel as shown or on any other type of suitable body member. The

center bit has cutting blades 30 which drill out the center of the bottom of the hole, and slush passageways 3| are provided for conveying slush to these blades. At the upper end of the core barrel the valve fitting shown in Fig. 1 is replaced with a simple head 32 having slush passageways 33 therethrough when the center bit is in use.

It will be understood that the splines will serve the same purpose in holding the centerbit down while drilling that it does in the case of the core barrel while taking a core.

It will be seen that the hold down and drive is simple and without moving parts to get out of order, that it serves as a hold down and drive only when in use in drilling and will permit ready withdrawal of the corebarrel without having to be unlatched.

Having described my invention, I claim:

1. In a coring apparatus, a retractible core barrel, and a part of said core barrel having a rearwardly facing driving surface projecting from the side wall of said core barrel, the lower portion of said surface being inclined downwardly and rearwardly with respect to the direction of rotation of said core barrel while drilling, and the upper portion of said surface being inclined to a lesser degree than the lower portion.

2. In a coring apparatus, a rotary core bit, a retractible core barrel, and cooperating spirally arranged driving splines on said core barrel and in said core bit respectively for driving said core barrel with said core bit, said splines extending downwardly and rearwardly with respect to the rotation of the bit while drilling and the upper ends of the splines in said core bit and the lower end of said splines on said core barrel and the upper ends of said splines in the bit being inclined at an angle other than a right angle to the axis of said core barrel, whereby in the event that the lower ends of said splines on the core barrel contact the upper ends of said splines in said bit as the core barrel is being lowered into place, said core barrel will rotate slightly in one direction or the other and continue its downward movement to its fully engaged position.

3. In a coring apparatus, a. rotary core bit, a retractible core barrel and cooperating spirally arranged driving splines on said core barrel and in said core bit, said splines being inclined downwardly and rearwardly with respect to the direction of rotation of said core bit in operation, and the splines in aid core bit and the spaces between the splines on said core barrel being tapered in an upward direction whereby they will be brought into closer engagement with each other as the core barrel moves downwardly.

4. In a coring apparatus, a rotary core bit, a retractible core barrel and cooperating spirally arranged driving splines on said core barrel and in said core bit, said splines'extending downward,- ly and rearwardly with respect to rotation of said core bit, the upper ends of the splines in said core bit and the upper ends of the spaces between the splines on said core barrel being squared with respect to the general direction of said splines respectively, whereby they may abut each other squarely as the core barrel moves downwardly to its operating position, to seat said core barrel and limit its downward movement.

5. A core barrel assembly adapted to be lowered through a drill stem and seated within a core bit and to be retrieved throughsaid drill stem, the various parts of said assembly being threadedly connected to each other, said assembly comprising a core barrel and a fitting on the upper end thereof, said fitting having external upwardly facing surfaces inclined with respect to the axis of said fitting in such a direction that when enga d by a downward flow of slush past said fitting they will tend to cause said fitting to rotate in a direction to tighten the threadsembly.

6. A core barrel assembly adapted to be lowered through a drill stem and seated within a core bit and to be retracted through the drill stem after a core has been taken comprising a core barrel and a valved fitting on the upper end thereof, said valved fitting including a valve chamber opening at its lower end into said c'ore barrel and at its upper end to the interior of the drill stem, and a double seating check valve within said valve chamber, said check valve being adapted to seat normally under the influence of gravity upon its lower seat to prevent down flow into the core barrel but to permit up flow therefrom, said valve being adapted to seat under an excessive up flow through said core barrel against its upper valve seat so as to prevent up flow through the core barrel as during the lowering of the core barrel through the drill stem.

'7. In a coring apparatus, a rotary core bit, a retractible core barrel, and cooperating driving parts on said barrel and on said bit for driving said core barrel with said bit, the parts on said core barrel having rearwardly facing driving surfaces projecting from the side wall of said core barrel, the lower portions of said surfaces being inclined downwardly and rearwardly with respect to the direction of rotation of said core barrel while drilling, the upper portions of said surfaces being inclined to a lesser degree than the lower portions, the spaces between the parts on saizi core barrel bein tapered in an upward direction, the parts on said bithaving active driving surfaces extending downwardly and rearwardly with respect to the directon of rotation of the bit while drilling, said cooperating parts as they engage being brought into closer engagemeans having rearwardly facing driving surfaces projecting from the side wall of said drilling means, the lower portions of said surfaces being inclined downwardly and rearwardly with respect to the direction of rotation of said drilling means while drilling, the upper portions of said surfaces being inclined to a lesser degree than the lower portions, the spaces between the parts on said drilling means being tapered in an upward direction, the parts on said bit having active driving surfaces extending downwardly and rearwardly with respect to the direction of rotation of the bit while drilling, said cooperating partsas they engage being brought into closer engagement with each other as the drilling means moves downwardly.

9. In a coring apparatus, a rotary core bit, a retractible center bit adapted to extend through the central opening of said bit, and cooperating driving parts on said center bit and on said core bit for driving said center bit with said core bit, the parts on said center bit having rearwardly facing driving surfaces projecting from the side wall of said center bit, the lower portions of said surfaces being inclined downwardly and rearwardly with respect to the direction of rotation of said center bit while drilling, the upper portions of said surfaces being inclined to a lesser degree than the lower portions, the spaces between the parts on said center bit being tapered in an upward direction, the parts on said bit hav- -\ing active driving surfaces extending downwardly and rearwardly with respect to the direction of rotation of the bit while drilling, said cooperating parts as they engage being brought into closer engagement with each other as the center bit moves downwardly.

10. In an apparatus of the character described, a retractible drilling member adaptedto be passed downwardly into and retracted from a core bit, and a part of said drilling member having a rearwardly facing driving surface projecting from the side wall of said drilling member, the lower portion of said surface being inclined downwardly and rearwardly with respect to the direction of rotation of said drilling member while drilling, and the upper portion of said surface being inclined to a lesser degree than the lower portion.

11. In an apparatus of the character described, a retractible center bit adapted to be passed downwardly into and retracted from a core bit, and a part of said center bit having a rearwardly facing driving surface projecting from the side wall of said center bit, the lower portion of said surface being inclined downwardly and rearwardly with respect to the direction of rotation of said center bit while drilling, and the upper portion of said surface being inclined to a lesser degree than the lower portion.

12. In a coring apparatus, a core bit, and a part in said core bit having an inwardly extending member carried by said core bit and providing a forwardly facing driving surface inclined downwardly and rearwardly with respect to the direction of rotation of the bit in drilling, said inwardly extending member being of less width at the top end than at the bottom end.

13. In a coring apparatus, a rotary core bit, a retractible core barrel, and cooperating driving parts on said barrel and on said bit for driving said core barrel with said bit, the part on said bit having an active driving surface progressing downwardly and rearwardly and in a direction opposite to that direction of rotation taken by said drill bit while drilling.

14. In a coring apparatus, a rotary core bit, a

retractible core barrel, and cooperating drivingbeneath a portion of said part on the 'bit when said barrel moves to its lowermost position in said bit while drilling.

15. In a coring apparatus, a rotary core bit, a retractible drilling means adapted to extend through the central opening of said bit, and cooperating driving parts on said drilling means and on said bit for driving said drilling means with said bit, the part on said bit having an active driving surface progressing downwardly and rearwardly and in a direction opposite to that direction of rotation takenby said drill bit while drilling.

16. In a coring apparatus, a rotary core bit, a retractible center bit adapted to extend through the central opening of said core bit, and cooperating driving parts on said two bits for driving said center bit with said core bit, the part on said rotary core bit having an active driving surface progressing downwardly and rearwardly and in a direction opposite to that direction of rotation taken by said center bit while drilling.

17. In a coring apparatus, a rotary core bit, a retractible drilling member adapted to extend through the central opening of said core bit, and

cooperating driving parts on said retractible drilling member and on said bit for driving said drilling member with said bit, both of said parts having active driving surfaces cooperating with the'active surfaces on the other parts and progressing downwardly and rearwardly and in a direction of rotation opposite to that direction of rotation taken by said drill bit while drilling.

18. In a coring apparatus, a retractible core barrel, and a part of said core barrel having a rearwardly facing driving surface projecting from the side wall of said core barrel, said surface progressing downwardly and rearwardly and in a direction opposite to that direction of retation taken by said core barrel while drilling.

19. In an apparatus of the character described, a retractible drilling member adapted to be passed downwardly into and retracted from a core bit, and a part on said drilling member having a rearwardly facing driving surface projecting from the side wall of said drilling member, said surface progressing downwardly and rearwardly and in a direction opposite to that direction of rotation taken by said drilling member while drilling.

20. In an apparatus of the character described, a center bit adapted to be passed downwardly into and retracted from a core bit, and a part on said center bit having a rearwardly facing driving surface projecting from the side wall of said center bit, said surface progressing downwardly and rearwardly and in a direction opposite to that direction of rotation taken by said center bit while drilling.

JOHN E. HOFFOSS. 

